الفهرس 
Behavior of AC carcinomaOnly 14 pages are availabe for public view
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Abstract
The AC of the larynx extends on the ventral side of the glottis in a vertical direction both above
and below the level of the vocal folds.
The AC is anatomically different from the rest of the larynx. AC represents a dense mass
of fibroelastic tissue, that is the confluence of the vocal ligament, the
thyroepiglottic ligament, the conus elasticus and the internal perichondrium of the thyroid
ala that forms a tendon. This tendon offers a dense barrier to glottic cancer, so that invasion
of the adjacent thyroid cartilage has not been observed in cancer that remains limited to the
glottic level.
The anatomy of the AC can be summarized asfollow:
The tendon has the same constituent of the perichondrium, but devoid of the blood vessels, which
make it more potent barrier than perichondrium against spread of cancer.
There is no insertion of the tendon into the thyroid
cartilage, only blending on the inner surface of the cartilage (No perforations were detected in
the thyroid cartilage)
The X space is the only zone devoid completely of the
perichondrium, but it is formed of very thick avascular band of fibrous tissue firmly adherent to
the thyroid cartilage.
The thyroid cartilage itself is another potent barrier against
invasion by malignancy.The electron microscopic study reveals that the AC is
formed of collagen fibers, elastic fibers, active fibroblasts (for new fibers deposition), and
ground substance, which support the opinion that the AC is not a weak point for cancer larynx to
spread into the thyroid cartilage.
The radiological study of the AC showed that;
Normally there is no soft tissue elapsed between the thyroid cartilage and the air column at the
level of the glottis, but the normal AC thickness (by CT) may reach 1-1.6 mm (as an upper limit).
We can depend on CT scanning with sagittal reformat for evaluation of the involvement of the AC
area.
There is some sort of correlation between the staging of the glottic tumor and the
progression of the AC thickness radiologically, this means that the enlargement of the
glottic tumor occurs in all direction with the same rate, and there is no specific growth rate
in the region of the AC.
The difference in the thickness of the AC radiologically in the same stage of the tumor can be
explained on the basis of the tumor grading and differentiation histopathologically, the proximity
of site of onset of the primary tumor to the AC.
There is increased incidence of thyroid cartilage destruction as the AC lesion increased in
thickness as well as
with increasing in the grade of malignancy in addition to the
presence of ossified thyroid cartilage.
There is no thyroid cartilage invasion was present in cases with T2 or T3 glottic
carcinoma with AC involvement, The only 2 cases with thyroid cartilage destruction
was evidenced in patients with T3 glottic carcinoma clinically, while documented to be T4
radiologically and histopathologically, also it were of poor histological differentiation
(excluded from our study).
In our study, the only special behavior of the cancer of the AC is that it grows superficially on
the mucosa more than deeply before it can penetrate the dense barrier of the AC until late stage
(large T3), and in the presence of ossified cartilage, at this stage it can invade this barrier
and reach to the thyroid cartilage.
The optimal treatment of the AC carcinomas is a controversial issue. Radiotherapy may not be the
ideal treatment for every patient with an early glottic tumor with AC involvement, radiating the
whole larynx instead of excising only the tumor bearing area is considered overkill by some
authors. On the contrary, Laser excision is a local treatment that can be repeated if necessary and
does not preclude the later use of radiotherapy, and also requires no or minimal hospitalization.